What is the ruling on supplicating with the words: "O Allah, we ask You for the intercession of Your Prophet" after the Tarawih prayer?

The supplication "O Allah, we ask You for the intercession of Your Prophet" is permissible, because the supplicant is asking Allah to grant him the intercession of His Prophet, not asking the Prophet directly for intercession. However, singling out this supplication after the Tarawih prayer is an innovation (bid'ah), due to the lack of any legal evidence indicating it. Supplication is an act of worship that is prescriptive (tawqifiyyah), and one must adhere to legal evidence therein.